DE102006042987A1 - Cleaning method for reflective optical element, particularly for soft X-ray and extreme ultraviolet wavelength range, and for operation of extreme ultraviolet lithography device, involves heating reflective optical element - Google Patents

Abstract

The method involves heating a reflective optical element (1) within the range of a catalytic top layer (4) on approximately one hundred fifty degree celsius and more, and supplying molecular hydrogen in the range of the catalytic top layer. The reflective optical element is heated on approximately one hundred seventy degree, particularly approximately two hundred degree celsius and more. The both steps are carried out during the operation of the reflective optical element. Independent claims are also included for the following: (1) a reflective optical element for the soft X-ray and extreme ultraviolet wavelength range, particularly for an extreme ultraviolet lithography device, which has an optically active coating on a substrate (2) an arrangement of two or multiple reflective optical elements, which has an optically active coating on a substrate (3) a projection system, particularly for an extreme ultraviolet lithography device, which has a reflective optical element (4) an exposure system, particularly for an extreme ultraviolet lithography device, which has a reflective optical element (5) an extreme ultraviolet lithography device, which has a reflective optical element and a hydrogen inlet.

Description

Field of the invention

The The present invention relates to a method of cleaning a reflective optical element, especially for the extreme ultraviolet and soft x-ray wavelength range, and to a method of operating an EUV lithography apparatus with a reflective optical Element.

In addition, refers the present invention relates to a reflective optical element or an array of reflective optical elements for the extreme ultraviolet and soft x-ray wavelength range, in particular for use in EUV lithography devices. Further, refers the invention on projection systems and exposure systems, in particular for one EUV lithography device, with at least one reflective optical Element as well as on EUV lithography devices with at least one reflective optical element.

Background and state of the technology

reflective optical elements for the extreme ultraviolet (EUV) and soft X-ray wavelength range (e.g., wavelengths between about 5 nm and 20 nm), such as photomasks or multilayer mirrors in particular in the lithography of semiconductor devices used. Since EUV lithography devices usually several have reflective optical elements, this one as possible high reflectivity have to ensure a sufficiently high overall reflectivity. The reflectivity and the life of the reflective optical elements can by Contamination of the optically used reflective surface of the reflective optical elements due to short-wave radiation together with residual gases in the operating atmosphere arises, be reduced. As usual in an EUV lithography device several reflective optical elements are arranged one behind the other, act even lower levels of contamination on each individual reflective optical element to a greater extent on the total reflectivity out.

The Depending on the composition of the residual gas atmosphere, contamination may be more likely be oxidative or carbonaceous. To counteract the contamination, is mainly trying to use the reflective optical elements To provide protective layers that are inert to the respective residual gases, as the surface the optical active surface of the reflective optical elements. In addition, different Cleaning methods closer investigated, with the help of which the reflective optical elements of contamination should be cleaned without their optical Properties significantly impaired become. For example, the approach is followed, especially carbonaceous Remove contamination by placing it in a cleaning chamber introduced atomic hydrogen that is with particular the carbonaceous contamination on the surface of the reflective element located in the cleaning chamber volatile Connections responded. The atomic hydrogen is added to e.g. by Heating of molecular hydrogen to about 2400 ° C with the help a filament won.

Indeed is not atomic hydrogen because of its very high reactivity easy to handle. His extraction with the help of a filament harbors as well the risk of introducing additional contaminants, the e.g. from the filament itself come.

Summary of the invention

It is therefore an object of the present invention, a method for cleaning of reflective optical elements or an adapted to suggest a reflective optical element, which is a simpler Handling allowed.

• – Aufheizen des reflektiven optischen Elements zumindest im Bereich der katalytischen Deckschicht auf ca. 150°C und mehr; und
• – Zuleiten von molekularem Wasserstoff, zumindest in den Bereich der katalytischen Deckschicht.

This object is achieved by a method for cleaning a reflective optical element, in particular for the soft X-ray and extreme ultraviolet wavelength range, with a catalytic cover layer, comprising the steps:

• - Heating the reflective optical element at least in the range of the catalytic cover layer to about 150 ° C and more; and
• - Supply of molecular hydrogen, at least in the range of the catalytic cover layer.

• – Aufheizen des reflektiven optischen Elements zumindest im Bereich der katalytischen Deckschicht auf ca. 150°C und mehr; und
• – Zuleiten von molekularem Wasserstoff, zumindest in den Bereich der katalytischen Deckschicht.

This object is also achieved by a method for operating an EUV lithography apparatus having at least one reflective optical element with a catalytic cover layer, comprising the steps of:

• - Heating the reflective optical element at least in the range of the catalytic cover layer to about 150 ° C and more; and
• - Supply of molecular hydrogen, at least in the range of the catalytic cover layer.

By providing reflective optical elements with a catalytic surface layer and providing sufficient energy by heating, molecular hydrogen can be split into atomic hydrogen directly on the catalytic surface layer. This not only has the advantage that now worked with molecular hydrogen who can, which can be handled much easier and less effort than atomic hydrogen, but also that the atomic hydrogen arises essentially at the place where it is needed, namely at the surface of the reflective optical element, in particular carbonaceous Contamination is to be cleaned. As a result, the probability of the reaction of the atomic hydrogen with regions outside of the reflective optical element to be cleaned, for example other components or inner walls of an EUV lithography device in which the reflective optical element with catalytic cover layer is located, is significantly reduced. Since neither, for example, glow wire devices for obtaining atomic hydrogen nor costly protective measures for supplying atomic hydrogen to the optical element to be cleaned are necessary, the cleaning process can not only for in-situ cleaning, but also for online or operando cleaning, ie the cleaning of reflective optical elements with catalytic protective layer within an EUV lithography device during their operation, so when irradiation of EUV radiation, exposure of a photomask and projection to use their structure on semiconductor wafers.

Of the on the heated catalytic top layer resulting atomic Hydrogen reacts particularly well with carbonaceous contamination volatile Links. But also oxidized surfaces can be due to the atomic hydrogen be reduced, which also reduces oxidative contamination becomes.

One greater The advantage is that when using the cleaning process during the Operation of the reflective optical element, the deposition of contamination reduced on it or in particular when using the method of Even avoid the beginning of the operation.

Further This object is achieved by a reflective optical element, in particular for the soft x-ray and extreme ultraviolet wavelength range, in particular for Use in an EUV lithography apparatus, solved, with an optically active coating on a substrate on the Radiation auszusetzenden page, with over a catalytic coating layer and with a heater. Likewise, this object is achieved by an arrangement of two or more reflective optical elements for the soft one Roentgen- and extreme ultraviolet wavelength range, in particular for Use in an EUV lithography apparatus, solved by which at least two reflective optical elements an optical active coating on a substrate on the radiation auszusetzenden Page with about it have a catalytic coating layer and an operating temperature of about 150 ° C and have more.

The Purification with catalytically produced atomic hydrogen is especially efficient for reflective optical elements that are not just a catalytic topcoat have, but also a separate heating device. So that can the reflective optical element are heated to the specific Favor cleaning process, or upon shutdown of the heater to the cleaning process throttle or interrupt. This is especially true for in-situ and the online or operando cleaning advantage. In addition, will by the specific heatability of the reflective optical element Ensures economic efficiency from an energy point of view. Likewise, it may also be constructive advantageous, not at everyone to provide a separate heating element for the reflective optical element, but about an optional external heater at least some of the reflective optical elements of an arrangement on one of the catalytic mentioned above Processes sufficient temperature to heat up. This can e.g. at compact arrangements with rather small distances between the individual reflective optical elements and not very large external dimensions of energetic Be more economical.

Finally will this object by a projection system and an exposure system, especially for an EUV lithography apparatus having at least one of the above reflective optical element and a hydrogen inlet as well as through an EUV lithography device with at least one above-mentioned reflective optical element and a hydrogen inlet dissolved. Likewise, this is achieved by a projection system and an exposure system, especially for an EUV lithography apparatus, and by an EUV lithography apparatus having two or more reflective optical elements for the soft X-ray and extreme ultraviolet wavelength range, from which at least two reflective optical elements an optical active coating on a substrate on the radiation auszusetzenden Page with about it have a catalytic coating layer and an operating temperature of about 150 ° C and have more.

Both the projection system and the exposure system as well as the EUV lithography device are designed to allow not only in situ, but also online or operando cleaning. As a result, the service life is significantly reduced, since not only to be cleaned reflective optical elements do not have to be removed, but also in particular the exposure process does not have to be interrupted. Since in such an operando process cleaning compariswei can be carried out easily, cleaning can be carried out more often or permanently. This increases between two cleaning cycles less contamination, which can be removed even by means of lower atomic hydrogen concentrations, or no contamination after. The gentler cleaning reduces impairments in the optical properties of the reflective optical element to be cleaned, for example caused by inhomogeneities on the optical surface. With continuous cleaning, even a state of equilibrium can be achieved, in which the contamination can be kept permanently at a negligible level. Also in exposure systems, projection systems and EUV lithography devices, it is possible either to provide individual heaters on individual reflective optical elements or to bring two or more reflective optical elements via a common heat source to an operating temperature of about 150 ° C and more.

advantageous Embodiments can be found in the dependent claims.

Brief description of the figures

The The present invention is intended to be better understood with reference to a preferred embodiment be explained in more detail. Show this

1 schematically an embodiment of a reflective optical element;

2 schematically an embodiment of an EUV lithography device with an exposure system and a projection system;

3 a flowchart for an embodiment of the cleaning method; and

4 a flowchart of an embodiment of the operating method for an EUV lithography device.

Detailed description of the invention

1 shows by way of example a reflective optical element 1 for the extreme ultraviolet and soft x-ray wavelength range, in particular for use in EUV lithography devices, eg as a photomask or as a mirror, which is located in a hydrogen-containing atmosphere. In the in 1 As shown, the reflective optical element has a substrate 2 on top of which an optically active coating 3 is applied. In the present example, the optically active coating is a multilayer system 3 , This is an alternatingly applied layer of a low-absorbing material (also called a spacer) and a strongly absorbing material (also called an absorber). This somehow simulates a crystal whose lattice planes correspond to the absorber layers at which Bragg reflection occurs. For the extreme ultraviolet and soft X-ray wavelength range, silicon is very often used for the spacer layers and molybdenum for the absorber layers. However, other material combinations are also suitable for the extreme ultraviolet and soft X-ray wavelength range, for example molybdenum / beryllium, ruthenium / silicon, molybdenum carbide / silicon, etc. In general, there should be a large difference in the refractive index in the range of the operating wavelength for the individual materials. Furthermore, layers of more than two materials can also be combined to form repeating layer units. In the present example, layers which act as diffusion barriers, such as, for example, silicon nitride, boron carbide, molybdenum carbide, etc., are also arranged between the actual absorber and spacer layers, such that even at elevated temperatures the layer structure of the multilayer system 3 preserved. The thicknesses of the individual layers as well as of the repeating layer units depend on the choice of material and the planned operating wavelength. The thicknesses of the individual layers as well as of the repeating layer units can be applied over the entire multilayer system 3 be constant or vary, depending on which reflection profile is to be achieved.

The multilayer system 3 is on the side of the reflective optical element 1 which is exposed to EUV or soft X-radiation. Above the multilayer system is a cover layer 4 from a catalytic material. On this top layer 3 If sufficient energy is supplied, for example in the form of heat, molecular hydrogen is split into atomic hydrogen. Advantageously, a transition metal, in particular group VIII, in pure form or as an alloy or as part of a compound for the catalytic cover layer 4 selected. Particular preference is given to ruthenium, rhodium, platinum, palladium, molybdenum, osmium, iridium, rhenium, nickel, silver, gold as catalytic cover layer material or metal oxides such as, for example, zinc oxide. Im in 1 example shown is, for example, a ruthenium layer. The thickness of the catalytic topcoat 4 is chosen so that the influence on the optical properties of the reflective optical element 1 as low as possible or by adjustments in the layer structure of the multilayer system 3 corrected as well as possible.

On the the multilayer system 3 opposite side has the reflective optical element 1 a heating device 5 on. In particular, in conventional heaters, with Joule heat work by guiding a wire-shaped electrical conductor flat on the underside of the substrate, this has the following advantage: Even with narrow guidance of the electrical conductor, so with small distances between adjacent sections of the electrical conductor, can not be homogeneous To achieve heating in the immediate vicinity of such a heater. Im in 1 In contrast, the amount of heat emanating from each conductor section can be in the substrate 2 and slightly even in the multilayer system 3 spread so that upon reaching the catalytic cover layer, here the ruthenium layer 4 , the temperature distribution over the entire surface is substantially homogeneous.

A homogeneous heating over the surface is especially with regard to the multilayer system 3 and important for online or operando cleaning. For inhomogeneous heating by different thermal expansion at different locations, the layer thicknesses in the multilayer system change differently and lead to an unintentional over the surface variation in reflection behavior, which can lead to unwanted aberrations especially in EUV lithography of larger area structures.

Of the on the heated catalytic top layer resulting atomic Hydrogen reacts particularly well with carbonaceous contamination volatile Links.

But also oxidized surfaces can through The atomic hydrogen can be reduced, which also oxidative Contamination is reduced.

In general, can be by direct contact of the heater 5 with the reflective optical element 1 a very efficient heat transfer even in vacuum at in situ or online or operando cleaning in an EUV lithography device or other X-ray optical device in which a corresponding reflective optical element is used, reach. Other heating devices may, for example, also be based on indirect heating by, for example, IR radiation. In particular, in arrangements of a plurality of reflective optical elements having smaller pitches, a heater mounted in the vicinity of one of the reflective optical elements can sufficiently heat the adjacent reflective optical elements as well. Likewise, it is also possible to use one or more heating devices or external heat sources independent of the reflective optical elements.

The catalytic topcoat 4 should be heated to at least about 150 ° C, so that a catalytic decomposition of molecular hydrogen into atomic hydrogen can take place in sufficient quantity for a cleaning effect. The hydrogen then reacts with particular carbonaceous contamination to volatile hydrocarbon compounds. The higher the temperature of the catalytic topcoat 4 is, the higher the rate at which it is covered with atomic hydrogen, which can then react with contamination. Preferably, the catalytic cover layer becomes 4 heated to a temperature of about 170 ° C, more preferably to about 200 ° C or more. Depending on the nature of the optically active surface, for example of the multilayer system 3 of the reflective optical element 1 It is also possible to use temperatures of approx. 250 ° C, approx. 300 ° C or far above. The amount of atomic hydrogen can also be controlled by the amount of molecular hydrogen supplied. Is the reflective optical element located 1 for cleaning purposes in a closed chamber, the partial pressure of the molecular hydrogen should be at least about 0.01 mbar in order to achieve a cleaning effect. In particular in the case of in-situ and online or operando cleaning, the partial pressure should be at a maximum of approximately 1 mbar in order not to impair the operation of the EUV lithography apparatus or of the exposure or projection system containing a reflective optical element with a catalytic cover layer , When cleaning in a dedicated cleaning chamber also partial pressures of more than 1 mbar can be used. At a high temperature of several hundred degrees Celsius, however, there is the danger that not only the contamination will be removed, but that there will be sufficient atomic hydrogen with sufficient effect that it will penetrate the uppermost layers of the reflective optical element to a greater extent 1 can diffuse into and thereby the properties of the reflective optical element 1 can worsen.

In a variant for reflective optical elements which are exposed to a very intense EUV or soft X-rays and thus an already high heat load, in particular for the usual case that not the entire surface of the reflective optical element is illuminated, the heater to the the optically active surface adjacent sides or even in the edge region are applied to the catalytic cover layer itself to bring the entire surface to a homogeneous temperature despite only local irradiation. In the case of a very small beam spot and a limited surface area that is optically used, the heating device can be provided on the sides or on the cover layer even when irradiation of lower intensity, since the optically used area has a sufficiently homogeneous temperature distribution Although the peripheral areas are heated sufficiently, the catalytic process for the decomposition of molecular hydrogen can take place. In extreme cases, in such a constellation, the catalytic cover layer can be provided only in the edge region, which is not used optically. However, the catalytic top layer often also takes over protective function against mechanical removal in other purification processes or against oxidation if oxygen, water or other oxygen-containing compounds such as, for example, alcohol or acetone should be present in the residual gas atmosphere.

It It should be noted that in addition to the number of cleaning to disposal standing hydrogen atoms also the carbon growth on reflective optical elements such as EUV mirrors indirectly with the intensity of the incident Radiation correlates. Because the EUV radiation or soft X-rays itself, or the photo- and secondary electrons generated by the irradiation leads already to a small extent for the breakdown of molecular hydrogen or hydrocarbon compounds in atomic hydrogen or Also, smaller carbonaceous molecules posing as contamination on the optically used area of the reflective optical element can deposit. Therefore it is in the processes that take place, so to speak self-regulating System in which there is a balance of carbon growth and Can form carbon cleaning.

In 2 schematically is an EUV lithography device 10 shown. Essential components are the beam-forming system 11 , the exposure system 14 , the photomask 17 and the projection system 20 ,

As a radiation source 12 For example, a plasma source or a synchrotron can serve. The emerging radiation in the wavelength range of about 5 nm to 20 nm is first in the collimator 13b bundled. Also, with the help of a monochromator 13a filtered out by varying the angle of incidence, the desired operating wavelength. In the aforementioned wavelength range are the collimator 13b and the monochromator 13a Usually designed as reflective optical elements, which can have a catalytic cover layer in other embodiments, which can be heated. Collimators are often cup-shaped reflective optical elements to achieve a focusing or collimating effect. The reflection of the radiation takes place on the concave surface, wherein no multilayer system on the concave surface is frequently used for the reflection, since the broadest possible wavelength range is to be reflected. The filtering out of a narrow wavelength band by reflection occurs at the monochromator, often with the aid of a lattice structure or a multilayer system. Regardless of how the desired reflection is caused at the collimator or monochromator, they may have a catalytic coating layer heated by, for example, a heater at the collimator and / or monochromator to clean them from contamination or to form contamination suppress.

The in the beam-forming system 11 In terms of wavelength and spatial distribution processed operating beam is then in the exposure system 14 introduced. Im in 2 The example shown has the exposure system 14 two mirrors 15 . 16 which both have a catalytic top layer and can be heated together or independently. The mirror 15 . 16 direct the beam onto the photomask 17 that has the structure on the wafer 21 should be displayed. At the photomask 17 it is also a reflective optical element for the EUV and soft wavelength range with heatable catalytic cover layer, which can not be cleaned in-situ or online or operando in the example shown here. However, since photomasks are replaced anyway depending on the manufacturing process, this has no serious negative consequences on the life of the EUV lithography device 10 , With the help of the projection system 20 becomes that of the photomask 17 reflected beam on the wafer 21 projected and thereby imaged the structure of the photomask on him. The projection system 20 has two heatable mirrors in the example shown 18 . 19 with catalytic topcoat on. It should be noted that both the projection system 20 as well as the exposure system 14 may each have only one or even three, four, five and more mirrors, of which a mirror or more about its own or one or more common heat sources or heating means can be heated and have catalytic cover layers. Likewise, you can choose either a heatable photomask 17 use with catalytic cover layer and expose it to a H ₂ atmosphere or not.

Im in 2 Example shown are both on the exposure system 14 as well as on the projection system 20 a feed 31 . 33 for molecular hydrogen, over which one can set either continuously or for cleaning cycles a hydrogen atmosphere. When heating the mirror 15 . 16 . 18 . 19 It should be noted that the heating capacity is adjusted to the EUV radiated power to which they are exposed if they each have their own heating system. In particular, the first mirror in the beam path 15 is exposed to a particularly high heat load, so that the heating power is lower than in the following mirroring 16 . 18 . 19 can be regulated. It should also be pointed out that, in contrast to conventional EUV lithography devices, it is possible to dispense with cooling devices, such as those provided in particular in the first mirror in the beam path, since in the present EUV lithography device the influence of the heat load is utilized and supported.

In addition, each one is a feed 32 on the exposure system 14 and a feed 34 on the projection system 20 provided, via which a connection with an electronegative element can be introduced, which can be deposited on the surface of the reflective optical elements. Namely, it has been found that reflective optical elements having a cap layer comprising a Group VIII transition metal can be effectively protected from contamination by a kind of protective layer of a thickness less even a monolayer based on an electronegative element. The electronegative element is adsorbed or chemisorbed by the Group VIII metal, thereby blocking surface sites that can not be occupied by other atoms or molecules. This effect also seems to extend to the nearest and second neighbor sites, which could possibly be explained by the electronegativity of the element. The occupation of surface areas prevents, inter alia, the adsorption of carbonaceous contamination.

In addition, will also increases the resistance of the topcoat to oxidation and the Absorption and the dissociation of oxygen on the surface layer surface prevented. Is particularly pronounced the effect of a ruthenium topcoat, where the surface areas be filled with sulfur. But also with cover layers of the metals rhodium, platinum, palladium, Iridium, silver, gold, ruthenium, molybdenum, osmium or rhenium, whose surface sites with the electronegative elements sulfur, iodine, phosphorus, arsenic or be filled with a cyanide group, can be contamination reduce or avoid.

advantageously, becomes a reflective optical element with a cover layer a transition metal Group VIII or gold or silver before first use by treating with a gaseous Compound containing an electronegative element or a cyanide group provided with a corresponding protective layer during the Operation of the reflective optical element or during interruptions the company replenished can be made by placing the appropriate gaseous compound of the surface of the Reflective optical element supplies. In this way is from At the beginning of a contamination effectively suppressed. One uses in particular Ruthenium topcoats Sulfur for filling the surface areas a, sulfur-containing gases are preferably introduced. Especially For example, preferred are hydrogen sulfide, dimethyl sulfide and thiophene. Combine the suppression of contamination with help a heated catalytic topcoat in a hydrogen-containing atmosphere with the the latter approach by appropriate choice of the cover sheet material, For example, you can run both processes in parallel, by containing the electronegative element or a cyanide group Connecting with such low partial pressure that the topcoat surface only partially covered with the electronegative element, so that still a sufficient amount of molecular hydrogen catalytically can be decomposed in atomic hydrogen. When using of ruthenium and sulfur In this case, also introduce hydrogen sulfide, with a Gas to enable both processes. On the other hand, you can also fall back on the second process, if, e.g. because of an oxygen or moisture leak a beginning oxidative contamination is detected, better by filling the surface sites can be countered with an electronegative element than with catalytically obtained atomic hydrogen.

In 3 the flow of an embodiment of the method for cleaning a catalytic overlay reflective optical element is shown in a flow chart.

This is an example of cleaning outside an EUV lithography device or an exposure or projection system. First, the reflective optical element to be cleaned is installed in a cleaning chamber (step 101 ). Thereafter, the cleaning chamber is evacuated (step 102 ), in order to simultaneously heat the reflective optical element to more than 200 ° C and to introduce molecular hydrogen into the cleaning chamber at a partial pressure of about 1 mbar (steps 103 . 104 ), whereby these two steps can optionally be carried out successively in any order. Subsequently, the temperature and the hydrogen atmosphere are maintained until the reflective optical element is cleaned (step 105 ). With such strong contamination that the catalytic top layer is already completely covered, so that can no longer run catalysis, you can also upstream of an additional conventional cleaning cycle, for example, by using a generated by a filament atomic hydrogen, which, however, can already be stopped before a Damage to the surface of the reflective optical element takes place since the final cleaning by the here described method is achieved.

In 4 FIG. 2 is a flowchart showing the sequence of an embodiment of the method for operating an EUV lithography apparatus with at least one catalytic layer reflective optical element. In this case, the at least one reflective optical element can be located in the exposure or in the projection system. It can also be the photomask. First, the EUV lithography apparatus is put into operation in the usual way (step 111 ). These include, among other things, the installation and the setting up of the reflective optical elements in a vacuum and the recording of the exposure process by irradiation of EUV or soft X-ray radiation. Thereafter, the at least one reflective optical element with catalytic cover layer is heated to more than 200 ° C and simultaneously introduced molecular hydrogen at a partial pressure of about 0.1 mbar (steps 112 . 113 ), whereby these two steps can optionally be carried out successively in any order. By doing this as soon as possible after the commissioning of the EUV lithography device, it can be effectively prevented that build up any appreciable contamination at all. Subsequently, the temperature and the hydrogen atmosphere during the further operation are maintained (step 114 ). Optionally, it may also be sufficient to heat the reflective optical elements with catalytic cover layer and supply hydrogen only at certain intervals.

The methods and components of an EUV lithography apparatus described herein allow a low-contamination and less expensive operation of EUV lithography devices with short life, resulting in increased efficiency of EUV lithography devices leads.

1

reflective optical element

2

substratum

3

multilayer

4

catalytic topcoat

5

heater

10

EUV lithography device

11

Beam shaping system

12

EUV radiation source

13a

monochromator

13b

collimator

14

exposure system

15

first mirror

16

second mirror

17

mask

18

third mirror

19

fourth mirror

20

projection system

21

wafer

31

Hydrogen supply

32

supply

33

Hydrogen supply

34

supply

101-105

steps

111-114

steps

Claims (17)

Method for cleaning a reflective optical Elements, in particular for the soft X-ray and extreme ultraviolet wavelength range, with a catalytic Covering layer with the steps: - heating up the reflective optical element at least in the region of the catalytic cover layer to about 150 ° C and more; and - Supply of molecular hydrogen, at least in the catalytic range Top layer. Method according to claim 1, characterized in that that the reflective optical element to about 170 ° C, preferably about 200 ° C and more is heated. Method according to claim 1 or 2, characterized that both steps during the operation of the reflective optical element. Method for operating an EUV lithography device with at least one reflective optical element for the soft one Roentgen- and extreme ultraviolet wavelength range with a catalytic Covering layer with the steps: - heating up the reflective optical element at least in the region of the catalytic cover layer to about 150 ° C and more; and - Supply of molecular hydrogen, at least in the catalytic range Top layer. Method according to claim 4, characterized in that that hydrogen with a partial pressure between about 0.01 mbar and about 1 mbar is supplied. Method according to claim 4 or 5, characterized that the at least one reflective optical element is heated homogeneously becomes. Reflective optical element ( 1 ) for the soft X-ray and extreme ultraviolet wavelength range, in particular for use in an EUV lithography apparatus, with an optically active coating ( 3 ) on a substrate ( 2 ) on the side to be exposed to the radiation, with a catalytic top layer ( 4 ) and with a heating device ( 5 ). Reflective optical element according to claim 7, characterized in that the catalytic covering layer ( 4 ) has a transition metal. Reflective optical element according to claim 7, characterized in that the catalytic covering layer ( 4 ) has a substance from the group ruthenium, rhodium, palladium, platinum, molybdenum, iridium, osmium, rhenium, nickel, silver, gold or zinc oxide. Reflective optical element according to one of claims 7 to 9, characterized in that the heating device ( 5 ) on the optically active coating ( 3 ) opposite side of the substrate ( 2 ) is arranged. Arrangement of two or more reflective optical elements ( 13a , b, 15 . 16 . 17 . 18 . 19 ) for the soft X-ray and extreme ultraviolet wavelength range, in particular for use in a lithography apparatus, of which at least two reflective optical elements ( 13a , b, 15 . 16 . 17 . 18 . 19 ) an optically active coating ( 3 ) on a substrate ( 2 ) on the side to be exposed to the radiation with a catalytic top layer ( 4 ) and have an operating temperature of about 150 ° C and more. Projection system ( 20 ), in particular for an EUV lithography apparatus, having at least one reflective optical element ( 18 . 19 ) according to claims 7 to 10 and a hydrogen inlet ( 33 ). Projection system ( 20 ), in particular for an EUV lithography apparatus, with two or more reflective optical elements ( 13a , b, 15 . 16 . 17 . 18 . 19 ) for the soft X-ray and extreme ultraviolet wavelength range, in particular for use in a lithography apparatus, of which at least two reflective optical elements ( 13a , b, 15 . 16 . 17 . 18 . 19 ) an optically active coating ( 3 ) on a substrate ( 2 ) on the side to be exposed to the radiation with a catalytic top layer ( 4 ) and have an operating temperature of 150 ° C and more. Exposure system ( 14 ), in particular for an EUV lithography apparatus, having at least one reflective optical element ( 15 . 16 ) according to claims 7 to 10 and a hydrogen inlet ( 31 ). Exposure system ( 14 ), in particular for an EUV lithography apparatus, with two or more reflective optical elements ( 13a , b, 15 16 . 17 . 18 . 19 ) for the soft X-ray and extreme ultraviolet wavelength range, in particular for use in a lithography apparatus, of which at least two reflective optical elements ( 13a , b, 15 . 16 . 17 . 18 . 19 ) an optically active coating ( 3 ) on a substrate ( 2 ) on the side to be exposed to the radiation with a catalytic top layer ( 4 ) and have an operating temperature of 150 ° C and more. EUV lithography apparatus ( 10 ) with at least one reflective optical element ( 15 . 16 . 17 . 18 . 19 ) according to claims 7 to 10 and a hydrogen inlet ( 31 . 33 ). EUV lithography apparatus ( 10 ) with two or more reflective optical elements ( 13a , b, 15 . 16 . 17 . 18 . 19 ) for the soft X-ray and extreme ultraviolet wavelength range, in particular for use in a lithography apparatus, of which at least two reflective optical elements ( 13a , b, 15 . 16 . 17 . 18 . 19 ) an optically active coating ( 3 ) on a substrate ( 2 ) on the side to be exposed to the radiation with a catalytic top layer ( 4 ) and have an operating temperature of 150 ° C and more.